From 3adee777ad0d328e76ca9015cb7924134a992e81 Mon Sep 17 00:00:00 2001 From: Brian Gerst Date: Thu, 16 Mar 2023 22:21:03 +0000 Subject: x86/smpboot: Remove initial_stack on 64-bit In order to facilitate parallel startup, start to eliminate some of the global variables passing information to CPUs in the startup path. However, start by introducing one more: smpboot_control. For now this merely holds the CPU# of the CPU which is coming up. Each CPU can then find its own per-cpu data, and everything else it needs can be found from there, allowing the other global variables to be removed. First to be removed is initial_stack. Each CPU can load %rsp from its current_task->thread.sp instead. That is already set up with the correct idle thread for APs. Set up the .sp field in INIT_THREAD on x86 so that the BSP also finds a suitable stack pointer in the static per-cpu data when coming up on first boot. On resume from S3, the CPU needs a temporary stack because its idle task is already active. Instead of setting initial_stack, the sleep code can simply set its own current->thread.sp to point to the temporary stack. Nobody else cares about ->thread.sp for a thread which is currently on a CPU, because the true value is actually in the %rsp register. Which is restored with the rest of the CPU context in do_suspend_lowlevel(). Signed-off-by: Brian Gerst Signed-off-by: David Woodhouse Signed-off-by: Usama Arif Signed-off-by: Thomas Gleixner Tested-by: Usama Arif Tested-by: Guilherme G. Piccoli Reviewed-by: David Woodhouse Link: https://lore.kernel.org/r/20230316222109.1940300-7-usama.arif@bytedance.com --- arch/x86/kernel/asm-offsets.c | 1 + 1 file changed, 1 insertion(+) (limited to 'arch/x86/kernel/asm-offsets.c') diff --git a/arch/x86/kernel/asm-offsets.c b/arch/x86/kernel/asm-offsets.c index 283dcd2f62c8..dc3576303f1a 100644 --- a/arch/x86/kernel/asm-offsets.c +++ b/arch/x86/kernel/asm-offsets.c @@ -115,6 +115,7 @@ static void __used common(void) OFFSET(TSS_sp1, tss_struct, x86_tss.sp1); OFFSET(TSS_sp2, tss_struct, x86_tss.sp2); OFFSET(X86_top_of_stack, pcpu_hot, top_of_stack); + OFFSET(X86_current_task, pcpu_hot, current_task); #ifdef CONFIG_CALL_DEPTH_TRACKING OFFSET(X86_call_depth, pcpu_hot, call_depth); #endif -- cgit v1.2.3